1. Field of the Invention
My invention is in the field of filing systems, particularly for small, single-sheet information units such as microfiche cards.
2. Prior Art
Hundreds of prior-art filing systems have been devised in attempts to find the best accommodation of two conflicting requirements: overall compactness, and title-block visibility. To the extent that certain of these attempts have succeeded, the resulting systems have generally been relatively elaborate and costly, and have afforded the user little or no control over the parameters of the title-block-display process.
In the particular area of microfiche filing systems the state of the prior art is exemplified by U.S. Pat. No. 3,913,250, which issued Oct. 21, 1975 to Arthur T. Spees.
Spees shows that selected backing cards in a file enclosure can be made to fan apart for inspection of the title areas of the backing cards, or the title areas of microfiche cards or the like placed between the backing cards.
The fanning effect is provided in part by increased thickness of each backing card along a line near the bottom edge of the card. To make use of this fanning effect, a user sets the length of the enclosure and manipulates the backing cards in certain ways.
Unfortunately, however, the number of cards which can fan out at one time, and the angles between adjacent fanned cards, are not under the user's control; such parameters are predetermined by geometrical factors. These factors are the basic thickness of each card itself, the amount of increased thickness provided, and the distance of said line from the bottom edge of each card. These factors are all established at the time of manufacture of the backing cards.
Thus the prior art leaves unsolved the problem of providing a simple, economical fan-type microfiche filing system whose user can control, at the time of use, in a continuously adjustable fashion, the parameters of the fanning action. My invention is addressed to this problem.